<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<script>
    var a = new Array(3);
    console.log(a);
    var b = new Array(3);

    var c = ['frank',true,30];
    console.log(c);
    console.log(typeof c); //object
    console.log(c instanceof Array);  //true 表示 c是数组，否则为其它类型


    //数组可保存不同数据类型的内容
    var c = ['frank',true,30,undefined,null];
    c[0];
    c[1];
    c[2];
    c[3];
    c[4];



</script>
</body>
</html>